Numerical modelling and implementation of ferrite cored eddy current probes

This paper focuses on the development of a magnetic moment method of calculating vector field quantities for a highly permeable ferrite cored eddy current probe. Basis functions are used in this method to replace the scattered field caused by the probe core in accordance with the surface equivalence theorem. These functions are further developed and tested for accuracy and convergence. An efficient material profile equation, independent of probe coil and basis function properties, is also designed and verified. Collocation point selection and optimisation is finally undertaken leading to the accurate determination of probe source coil impedance. The accuracy of calculation is verified using an industry standard finite element solver.